In general, systems that perform data transfer to and from a processing unit either operate in a direct memory transfer access (DMA) mode or a streaming mode. In the DMA mode, the transfer of data between an I/O device and a memory unit is facilitated without the direct control of a central processing unit (CPU). Data can either be transferred from memory to an I/O device (a memory source transfer) or from an I/O device to memory (a memory destination transfer). DMA transfers typically involve the transfer of one or more blocks of data, as data transfers of only a few bytes of data are often performed more efficiently under the direct control of the CPU.
In a streaming mode on the other hand, data is streamed directly to the device requesting the data without being stored first in a local or host memory. The addressing information required for a DMA interface is not required when operating in a streaming mode.
DMA I/O interfaces may include, for example, the PCI, PCI 2.0, PCI 2.1, PCI 2.2, PCIX, Infiniband by Intel, and HyperTransport. Streaming interfaces may include, for example, the Packet-Over-SONET Physical-Layer Three (POS-PHY3) referred to as a PL3 interface, SPI 4, and GMII as well as other packet interfaces. In general, data is retrieved from DMA-type interfaces while data is pushed from streaming-type interfaces. Because each type of interface may have unique requirements, processing cores and their associated support systems are generally designed specifically for interfacing with one particular type of interface. This unfortunately requires a significant redesign of a processing core for each type of interface, which among other things, increases costs as well as increases time-to-market.
Thus, there is a general need for improved system and method to interface with a processing core. There is also a general need for a system and method that reduces design costs and time-to-market while also providing a flexible interface for both streamed and DMA data. There is also a general need for a system and method that provides a common bus interface for a processing core. There is also a general need for a system and method that provides for the transfer of both streaming and DMA data. There is also a general need for a system and method a system and method that may allow a processing core to communicate high-speed data with a several different types of interfaces including DMA interfaces and streaming interfaces.